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Bluetooth 4.0 support and iPhone 4

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Q: With cool new Bluetooth accessories starting to appear on the market, I’m wondering if my iPhone 4 will support Bluetooth 4.0 in iOS 6? I know that Apple added stereo audio support for older iPhones and iPods a few years ago as part of an iOS upgrade, so I’m hoping they might do the same for Bluetooth 4.

- Jon

A: Unfortunately, this seems extremely unlikely both for technical reasons as well as Apple’s general history when it comes to adding features to older devices.

From a hardware point of view, it’s important to understand the difference between a Bluetooth profile, such as A2DP, and a Bluetooth specification, such as Bluetooth 4.0. Bluetooth profiles are software-based and can be added simply by providing new drivers or OS components, while Bluetooth specifications are based entirely within the hardware chipsets in most cases, with limited upgradeability depending on the chips that are being used.

The iPhone 4 uses a single-band Broadcom BCM4329 chip for Bluetooth the 2.1 + EDR specification and 802.11b/g/n Wi-Fi. This is also the chip used in the third- and fourth-generation iPod touch, with a dual-band version used in the iPad, iPad 2 and second-generation Apple TV to provide 5Ghz Wi-Fi in additional to the standard 2.4GHz band.

In contrast, the iPhone 4S uses the single-band version of the Broadcom BCM4330 which is basically the next-generation version of the same chip, providing support for the Bluetooth 4.0 + HS specification.

Broadcom does indicate that the BCM4329 chip includes “provisions supporting future specifications” but it is unclear whether this means that it could actually be firmware upgraded to Bluetooth 4.0 or not, since it’s not always possible to include provisions for unknown specifications. Regardless, however, such an update would need to come from Broadcom, not Apple, and there is no indication that Broadcom has released—or ever will release—such an update. Keep in mind that the BCM4325 used in the iPhone 3GS and second-generation iPod touch noted similar “provisions” but no additional software features were ever provided beyond the addition of support for the A2DP profile in iOS 3.0, which as mentioned earlier is a software-based feature.

It’s also worth noting that Apple began using the Broadcom family of chipsets in 2008 with the second-generation iPod touch, and every Broadcom chip used since that time has also supported FM radio. This has led to repeated speculation that FM radio features would appear in an iOS update somewhere along the way, and that Apple chose this chip because it was planning to add FM radio features. Ultimately, however, this support never materialized, and it seems clear that the FM radio capabilities were simply an unnecessary extra feature that Apple received with the Broadcom chips.